The sandwich bags are the kind were the end just folds over (lame). The grocery basket is this size. So how many days worth of food she can carry in the basket would depend on the types of food she's putting on it! On average it would hold a maximum of four days of food, but if she's particularly ambitious she could probably puzzle-piece them in there to fit another day or two. The more food is put in it, however, the heavier and more tedious it gets to carry.